U.S. patent application number 15/734959 was filed with the patent office on 2021-07-29 for coexistence of radar probing and wireless communication.
The applicant listed for this patent is Sony Corporation. Invention is credited to Erik BENGTSSON.
Application Number | 20210231771 15/734959 |
Document ID | / |
Family ID | 1000005563894 |
Filed Date | 2021-07-29 |
United States Patent
Application |
20210231771 |
Kind Code |
A1 |
BENGTSSON; Erik |
July 29, 2021 |
COEXISTENCE OF RADAR PROBING AND WIRELESS COMMUNICATION
Abstract
A method of operating a wireless communication device (101, 102)
includes 5 performing at least one beam sweep (300-304) to identify
one or more beams (311-313, 331-333, 311A-313A, 331A-333A) for
communication on a wireless link (111) between the wireless
communication device (101, 102) and a further wireless
communication device (101, 102). The method also includes
determining one or more directions (205) based on the at least one
beam sweep. The method also includes performing radar probing (200)
along the one or more directions (260-263).
Inventors: |
BENGTSSON; Erik; (Eslov,
SE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Sony Corporation |
Tokyo |
|
JP |
|
|
Family ID: |
1000005563894 |
Appl. No.: |
15/734959 |
Filed: |
May 28, 2019 |
PCT Filed: |
May 28, 2019 |
PCT NO: |
PCT/EP2019/063850 |
371 Date: |
December 3, 2020 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G01S 7/023 20130101;
H04B 7/0695 20130101 |
International
Class: |
G01S 7/02 20060101
G01S007/02; H04B 7/06 20060101 H04B007/06 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 6, 2018 |
SE |
1830181-2 |
Claims
1. A method of operating a wireless communication device,
comprising: performing at least one beam sweep to identify one or
more beams for communication on a wireless link between the
wireless communication device and a further wireless communication
device, determining one or more directions based on the at least
one beam sweep, and performing radar probing along the one or more
directions.
2. The method of claim 1, further comprising: establishing whether
beam correspondence is provided on the wireless link, and
activating said performing of the radar probing along the one or
more directions if there is beam correspondence.
3. The method of claim 1, wherein the radar probing is performed in
response to identifying the one or more beams.
4. The method of claim 1, further comprising: communicating a
control signal on the wireless link indicative of at least one
radar-probing constraint, and performing the radar probing in
accordance with the at least one radar-probing constraint.
5. The method of claim 4, wherein the radar-probing constraint
comprises at least one of a transmit power restriction, a timing
restriction, a frequency band restriction, and a spatial
restriction.
6. The method of claim 1, wherein the at least one beam sweep
comprises a receive beam sweep of a pilot signal, wherein the
receive beam sweep comprises measurements of a received signal
strength of the pilot signal, wherein the one or more beams are
identified based on the received signal strength.
7. The method of claim 6, wherein the receive beam sweep comprises
a measurement of a spectral power level due to a signal originating
from one or more further wireless communication devices, wherein at
least one of the one or more directions and a transmit power of the
radar probing are determined based on the spectral power level.
8. The method of claim 1, wherein the at least one beam sweep
comprises a transmit beam sweep of a pilot signal, wherein the one
or more beams are identified based on a feedback signal associated
with the transmit beam sweep.
9. The method of claim 1, further comprising: setting a transmit
power of the radar probing based on at least one of a received
signal strength of a pilot signal of the at least one beam sweep
and a spectral power level of a receive beam sweep of the at least
one beam sweep.
10. The method of claim 1, wherein the at least one beam sweep is
allocated to a first frequency band, wherein the communication is
allocated to a second frequency band which is included in the first
frequency band, wherein the radar probing is optionally allocated
to a third frequency band which is larger than the second frequency
band.
Description
TECHNICAL FIELD
[0001] Various examples of the invention relate to performing a
beam sweep to identify one or more beams for communication on a
wireless link. Various examples of the invention relate to
performing radar probing.
BACKGROUND OF THE INVENTION
[0002] Object detection, for example to localize an object and/or
to determine a movement of an object, may be advantageous in
several use cases such as vehicle control, monitoring of buildings
and sites, and navigation.
[0003] Radar probing enables accurate object detection. Radar
probing employs radio waves at frequencies in the range of, e.g.,
20 GHz-80 GHz to determine the range, angle or velocity of objects.
Pulsed radio waves or continuous radio waves may be employed as
radar signals.
[0004] Modern wireless communication networks--e.g., Third
Generation Partnership (3GPP) New Radio (NR) 5G technology--also
employ radio wave carriers at frequencies in the range of 20 GHz-80
GHz.
[0005] Hence, there may be interference between wireless
communication and radar probing. This may specifically apply where
a wireless communication device (sometimes also referred to as user
equipment, UE) that is connectable to the wireless communication
network is equipment with radar probing functionality.
SUMMARY
[0006] A need exists for advanced techniques to provide for
co-existence between radar probing and wireless communication.
[0007] This need is met by the features of the independent claims.
The features of the dependent claims define embodiments.
[0008] A method of operating a wireless communication device
includes performing at least one beam sweep to identify one or more
beams for communication on a wireless link between the wireless
communication device and a further wireless communication device.
The method also includes determining one or more directions based
on the at least one beam sweep. The method also includes performing
radar probing along the one or more directions.
[0009] A computer program or computer program product includes
program code. The program code can be executed by at least one
processor. Executing the program code causes the at least one
processor to perform a method of operating a wireless communication
device. The method includes performing at least one beam sweep to
identify one or more beams for communication on a wireless link
between the wireless communication device and a further wireless
communication device. The method also includes determining one or
more directions based on the at least one beam sweep. The method
also includes performing radar probing along the one or more
directions.
[0010] For example, it may be possible that the one or more
directions are determined to be offset from the one or more beams
identified based on the at least one beam sweep.
[0011] The method may further include selecting the one or more
beams from a beam codebook based on the at least one beam sweep.
The method may further include determining the one or more
directions based on non-selected beams of the beam codebook.
[0012] The method may further include establishing whether beam
correspondence is provided on the wireless link. The method may
further include activating said performing of the radar probing
along the one or more directions if there is beam
correspondence.
[0013] For example, the performing of the radar probing may be
selectively activated if there is beam correspondence; hence, if
there is no beam correspondence, the radar probing may not be
activated.
[0014] The at least one beam sweep may include at least one of a
receive beam sweep and a transmit beam sweep.
[0015] For example, the radar probing may be performed in response
to identifying the one or more beams.
[0016] For example, the method may further include communicating a
control signal on the wireless link indicative of at least one
radar-probing constraint. The method may also include performing
the radar probing in accordance with the at least one radar-probing
constraint.
[0017] For example, the radar-probing constraint may include at
least one of a transmit power restriction, a timing restriction, a
frequency band restriction, and a spatial restriction.
[0018] The spatial restriction may be with respect to the one or
more directions determined for the radar probing.
[0019] For example, the at least one beam sweep may include a
receive beam sweep of a pilot signal. The receive beam sweep may
include measurements of a received signal strength of the pilot
signal, wherein the one or more beams are identified based on the
received signal strength.
[0020] It may be possible that multiple pilots signals are
communicated, e.g., different pilot signals on different beams.
[0021] For example, the at least one beam sweep may include a
transmit beam sweep of a pilot signal. The one or more beams max be
identified based on a feedback signal associated with the transmit
beam sweep.
[0022] For example, the method may further include setting a
transmit power of the radar probing based on a received signal
strength of a pilot signal of the at least one beam sweep.
[0023] For example, the at least one beam sweep may be allocated to
a first frequency band. It would be possible that the communication
is allocated to a second frequency band which is included in the
first frequency band.
[0024] The radar probing may be allocated to a third frequency band
which is larger than the second frequency band.
[0025] For example, the method may further include: determining
whether the wireless communication device is cleared-to-probe. If
the wireless communication device is cleared-to-probe, the radar
probing may be performed spatially unrestricted.
[0026] A wireless communication device is configured to perform at
least one beam sweep to identify one or more beams for
communication on a wireless link between the wireless communication
device and a further wireless communication device. The wireless
communication device is also configured to determine one or more
directions based on the at least one beam sweep. The wireless
communication device is also configured to perform radar probing
along the one or more directions.
[0027] It is to be understood that the features mentioned above and
those yet to be explained below may be used not only in the
respective combinations indicated, but also in other combinations
or in isolation without departing from the scope of the
invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] FIG. 1 schematically illustrates a wireless communication
system according to various examples.
[0029] FIG. 2 schematically illustrates the wireless communication
system of FIG. 1 in greater detail.
[0030] FIG. 3 is a flowchart of a method according to various
examples.
[0031] FIG. 4 schematically illustrates a beam sweep according to
various examples.
[0032] FIG. 5 schematically illustrates identifying one or more
beams for wireless communication and performing radar probing
according to various examples.
[0033] FIG. 6 schematically illustrates identifying one or more
beams for wireless communication and performing radar probing
according to various examples.
[0034] FIG. 7 schematically illustrates directions of the radar
probing according to various examples.
[0035] FIG. 8 schematically illustrates frequency bands used by a
beam sweep, wireless communication, and radar probing according to
various examples.
DETAILED DESCRIPTION OF EMBODIMENTS
[0036] In the following, embodiments of the invention will be
described in detail with reference to the accompanying drawings. It
is to be understood that the following description of embodiments
is not to be taken in a limiting sense. The scope of the invention
is not intended to be limited by the embodiments described
hereinafter or by the drawings, which are taken to be illustrative
only.
[0037] The drawings are to be regarded as being schematic
representations and elements are not necessarily shown to scale.
Rather, the various elements are represented such that their
function and general purpose become apparent to a person skilled in
the art. Any connection or coupling between functional blocks,
devices, components, or other physical or functional units shown in
the drawings or described herein may also be implemented by an
indirect connection or coupling. A coupling between components may
also be established over a wireless connection. Functional blocks
may be implemented in hardware, firmware, software, or a
combination thereof.
[0038] Hereinafter, techniques that facilitate coexistence between
radar probing and communication on a wireless link (wireless
communication) are described. Specifically, the techniques
described herein facilitate a UE to implement, both, radar probing
and wireless communication.
[0039] Radar probing may be employed for object detection and/or
positioning use cases. Radar probing may include transmission of
radar signals, e.g., pulsed or continuous radio waves, from a
wireless communication device such as a UE. The reflected radar
signals, sometimes referred to as echo or secondary radar signals,
are received at the wireless communication device or a further
wireless communication device. The secondary radar signals can be
analyzed by the wireless communication device and/or by a further
wireless communication device. A receive property of the reflected
radar signals can be analyzed. For example, the receive property
may be selected from the group comprising: a phase offset; a
time-of-flight; an amplitude; a path loss; a frequency shift; an
angle of arrival; and a polarization. Thereby, a distance, and/or a
size, and/or a speed, and/or a direction of movement, and/or an
acceleration of an object providing the reflection can be
determined.
[0040] As a general rule, wireless communication described herein
can be implemented according to various techniques. For example,
wireless communication can be implemented by a cellular network.
For example, a 3GPP NR 5G cellular network can be used. Here, a
mm-wave frequency band can be used for the wireless communication.
Hereinafter, primarily techniques of wirelessly communicating
between a UE and a base station (BS) of a communication system
implemented by a cellular network are described. As a general,
rule, similar techniques may also be applied for other
communication systems, e.g., in a peer-to-peer communication such
as on a sidelink channel, or communication between a UE and an
access point, etc.
[0041] The direction of communicating from the BS to the UE is
labeled downlink (DL) direction; and the direction of communicating
from the UE is labeled uplink (UL) direction. As a general rule,
various example techniques described herein for DL transmission may
be equally applied to UL transmission; and vice versa.
[0042] For cost and size reasons, it may be advantageous to re-use
the same hardware for radar probing and wireless communication. The
hardware is often designed for operation in a dedicated frequency
range. Then, radar probing and wireless communication can be
implemented in at least overlapping frequency bands. Then, there is
a potential for interference between radar probing and wireless
communication.
[0043] Various techniques are based on the finding that the
interference between radar probing and wireless communication can
depend on beamforming employed for the wireless communication.
[0044] According to various examples, the wireless communication
includes beamforming. One advantage of beamforming is the ability
to transmit on high carrier frequencies by increasing antenna
aperture, e.g., above 6 GHz and even up to 60 GHz or beyond. Large
bandwidths may be achieved. Another advantage of beamforming is the
availability of spatial multiplexing, thereby increasing spectral
efficiency. The overall antenna efficiency can be increased. To
implement beamforming, an antenna panel can implement
phase-coherent transmission in accordance with certain values
determined for antenna weights of multiple antenna elements of the
antenna panel, thereby creating a transmission directivity. Here,
the gain in a certain direction is often several dBs higher than
the gain from a single antenna element (beamforming gain). The use
of multiple antenna elements is sometimes referred to as Multiple
Input Multiple Output (MIMO). The amplitude and phase relationship
between the different antenna elements are specified by the
specific values of the antenna weights, where each value of the
antenna weights is indicative of the amplitude and phase of a given
antenna element of an antenna panel. Different values of the
antenna weights are associated with different beams of the
beamformed transmission; beams may differ in terms of direction,
beam width, etc. By changing the value of the antenna weights or
alternate between using different antenna elements to form beams,
it is possible to switch between different beams (beam switching).
Different gain can be achieved for different directions. Typically,
the beamforming gain by transmitting and/or receiving along the
appropriate beam can be significant. Attenuation is observed for
non-appropriate beams.
[0045] As a general rule, beamforming may be employed for receiving
signals (receive beamforming) and/or for transmitting signals
(transmit beamforming). Receive beamforming uses a receive beam.
Transmit beamforming uses a transmit beam.
[0046] As a further general rule, beamforming may be implemented in
uplink (UL) and/or in downlink (DL).
[0047] When implementing a beamforming, the direction of the one or
more beams may have a significant impact on the link performance.
This is because of the transmission characteristics varying for
different spatial propagation paths that are defined by the beams.
For example, a particular low-path loss may be expected for
transmission along a line-of-sight spatial propagation channel.
Generally, a beam oriented in the right direction will improve the
link budget with many dBs, according to the beamforming gain;
communication along inappropriate beams will result in strong
attenuation.
[0048] According to various examples, at least one beam sweep may
be employed to determine one or more beams that have a high
beamforming gain. Specifically, the appropriate orientation of the
beam to be used has to be determined. In a beam sweep, one or more
reference signals (sometimes also referred to as pilot signals) are
transmitted or received. A DL beam sweep including DL pilot signals
can be used. Also, an UL beam sweep including UL pilot signals can
be used. Also, a sidelink beam sweep between two UEs can be used.
Based on a receive property of pilot signals, it is then possible
to identify the appropriate beam. For example, a DL transmit beam
sweep may be employed at the BS and a time-synchronized DL receive
beam sweep may be employed at the UE. Alternatively or
additionally, it would also be possible to perform an UL transmit
beam sweep at the UE and perform a time-synchronized UL receive
beam sweep at the BS. Here, a beam sweep may include transmission
and/or reception of pilot signals on multiple beams. Pairs of beams
providing good beamforming gain can then be selected for the
wireless communication.
[0049] Using a beam sweep to determine one or more beams is
sometimes referred to as a codebook (CB) operational mode. The CB
operational mode may determine a beam by selecting a given beam
from a plurality of predefined candidate beams. As such, the CB
operational mode may determine associated values for the antenna
weights from a plurality of predefined candidate values of the
antenna weights. For example, these candidate values may be
included in a CB. Each entry in the CB may be associated with a
candidate beam. Details of such CB-based beam management including
beam sweeps are, e.g., described in 3GPP TSG RAN WG1 meeting #86,
R1-166089; R1-167466; R1-167543; R1-166389.
[0050] According to various examples, a wireless communication
device can be operated to perform at least one beam sweep. The beam
sweep is to identify one or more beams for the wireless
communication. Then, it is possible to determine one or more
directions based on the at least one beam sweep. It is then
possible to perform radar probing along the one or more directions
(radar-probing directions).
[0051] As a general rule, various options are available for
determining the one or more directions based on the beam sweep. In
one example, it would be possible to determine the one or more
directions to be offset from the one or more beams. Offset can
correspond to determining the one or more directions such that they
differ from the one or more beams. For example, the one or more
directions can point to different points in the environment if
compared to the one or more beams.
[0052] In a specific example, using a CB operational mode, a
transmit beam and/or a receive beam for wireless communication can
be identified at the UE. The UE, based on a corresponding beam
list, may be aware in what directions the BS can be reached. Then,
according to various examples, one or more radar-probing directions
that are offset from one or more beams in such a beam list can be
used for radar operation with low chance for interference. In some
examples, the UE may perform repeated receive beam sweeps to
populate a beam list for the wireless communication.
[0053] If the UE reported beam correspondence--i.e., a condition
where reciprocity of the path loss is provided for a transmit beam
having certain antenna weights and a receive beam having these
antenna weights--the list of all or at least some beams of CB with
the exception of the beams selected for wireless communication and
included in the beam list then may define the radar-probing
directions. Thus, generally speaking, one or more beams may be
selected from a CB; the one or more radar-probing directions may
then be determined based on the non-selected beams of the CB.
[0054] Such techniques of implementing radar probing may be
referred to as semi-unsanctioned radar probing. With
semi-unsanctioned it is meant that the UE may perform radar probing
on the determined one or more radar-probing directions without a
need of notifying the BS of the one or more radar-probing
directions. Thus, the radar probing may be triggered by and be in
response to identifying the one or more beams for the wireless
communication or, generally, may be triggered by and be in response
to the beam sweep; intermediate control signaling with the BS may
not be required.
[0055] Nonetheless, according to some examples, there may be DL
control signaling by means of which the BS can restrict one or more
operational parameters of the UE performing the radar probing,
e.g., in case interference in the cell increases. Corresponding
radar-probing constraints may include one or more of: a transmit
power restriction; restricted directions as part of a spatial
restriction; a timing restriction; a frequency band restriction;
etc.
[0056] Further, the UE may restrict the one or more radar-probing
directions with respect to other UEs, if it detects energy
transmitted from the other UEs as the UE performs the receive beam
sweep. For this, the spectral power level may be determined;
thereby, even without being able to decode and/or demodulate
communication by the other UEs, it is still possible to conclude
back on where the other UEs are located.
[0057] It is also possible to set a transmit power of the radar
probing based on the spectral power level. For example, if it is
judged that one or more other UEs are in close vicinity--due to a
high spectral power level--then the transmit power may be
appropriately adjusted, e.g., lowered.
[0058] FIG. 1 schematically illustrates a wireless system 100 that
may benefit from the techniques disclosed herein. The communication
system may be implemented by a 3GPP-standardized network such as
3G, 4G, or upcoming 5G NR. Other examples include point-to-point
networks such as Institute of Electrical and Electronics Engineers
(IEEE)-specified networks, e.g., the 802.11x Wi-Fi protocol or the
Bluetooth protocol. Further examples include 3GPP NB-IOT or eMTC
networks.
[0059] The system 100 includes a BS 101 and a UE 102. A wireless
link 111 is established between the BS 101--e.g., a gNB in the 3GPP
NR framework--and the UE 102. The wireless link 111 includes a DL
wireless link from the BS 101 to the UE 102; and further includes
an UL wireless link from the UE 102 to the BS 101. Time-division
duplexing (TDD), frequency-division duplexing (FDD), and/or
code-division duplexing (CDD) may be employed for mitigating
interference between UL and DL. Likewise, TDD, FDD, CDD and/or
spatial division duplexing (SDD) may be employed for mitigating
interference between multiple UEs communicating on the wireless
link 111 (not shown in FIG. 1).
[0060] The wireless link 111 may occupy frequencies above 6 GHz.
mmWave technology may be employed.
[0061] The UE 102 may be one of the following: a smartphone; a
cellular phone; a tablet; a notebook; a computer; a smart TV; an
MTC wireless communication device; an eMTC wireless communication
device; an IoT wireless communication device; an NB-IoT wireless
communication device; a sensor; an actuator; etc.
[0062] FIG. 2 schematically illustrates the BS 101 and the UE 102
in greater detail.
[0063] The BS 101 includes a processor 1011 and an interface 1012,
sometimes also referred to as frontend. The interface 1012 is
coupled via antenna ports (not shown in FIG. 2) with an antenna
panel 1013 including a plurality of antennas 1014. In some
examples, the antenna panel 1013 may include at least 30 antennas
1014, optionally at least 110 antennas, further optionally at least
200 antennas. Sometimes, a scenario implementing a large number of
antennas 1014 is referred to as full dimension multi-input
multi-output (FD-MIMO) or massive multi-input multiple-output
(Massive MIMO, MaMi). Each antenna 1014 may include one or more
electrical traces to carry a radio frequency current. Each antenna
1014 may include one or more LC-oscillators implemented by the
electrical traces. Each trace may radiate electromagnetic waves
with a certain beam pattern. In some examples the BS 101 may
include multiple antenna panels (not illustrated in FIG. 2).
[0064] The processor 1011 and the memory 1015 form a control
circuit.
[0065] The BS 101 further includes a memory 1015, e.g., a
non-volatile memory. The memory may store program code that can be
executed by the processor 1011. Executing the program code may
cause the processor 1011 to perform techniques with respect to
participating in a wireless communication on the wireless link 111,
communicating one or more UL and/or DL pilot signals, performing UL
receive beam sweeps and/or DL transmit beam sweeps, etc.
[0066] The UE 102 includes a processor 1021 and an interface 1022,
sometimes also referred to as frontend. The interface 1022 is
coupled via antenna ports (not shown in FIG. 2) with an antenna
panel 1023 including a plurality of antennas 1024. In some
examples, the antenna panel 1023 may include at least 6 antennas,
optionally at least 16 antennas, further optionally at least 32
antennas. Generally, the antenna panel 1023 of the UE 102 may
include fewer antennas 1024 than the antenna panel 1013 of the BS
101. Each antenna 1024 may include one or more electrical traces to
carry a radio frequency current. Each antenna 1024 may include one
or more LC-oscillators implemented by the electrical traces. Each
trace may radiate electromagnetic waves with a certain beam
pattern. Also the UE 102 may include multiple antenna panels 1023
(not illustrated in FIG. 2).
[0067] The processor 1021 and the memory 1025 form a control
circuit.
[0068] The UE 102 further includes a memory 1025, e.g., a
non-volatile memory. The memory 1025 may store program code that
can be executed by the processor 1021. Executing the program code
may cause the processor 1021 to perform techniques with respect to
participating in a wireless communication the wireless link 111,
communicating one or more UL and/or DL pilot signals, performing UL
transmit beam sweeps and/or DL receive beam sweeps, performing
radar probing, etc.
[0069] FIG. 2 also illustrates aspects with respect to propagation
channels 151. FIG. 2 schematically illustrates that different
propagation channels 151 (dashed lines in FIG. 2) are implemented
on the wireless link 111. The different propagation channels 151
are associated with different pairs of beams 311, 331 (in FIG. 2,
for sake of simplicity, only a single beam 311 implemented by the
UE 102 and a single beam 331 implemented by the BS 101 are
illustrated). For example, to implement a certain propagation
channel 151 for DL communication, a certain DL transmit beam 331
may be selected for the antenna panel 1013 of the BS 101 and a
corresponding DL receive beam 311 may be selected for the antenna
panel 1023 of the UE 102.
[0070] As a general rule, a given beam may be implemented by using
certain values of the antenna weights of the antennas 1014, 1024 of
the respective antenna panel 1013, 1023. Sometimes, the antenna
weights are also referred to as steering vectors or precoding
parameters. Accordingly, different beams 311, 331 may be
implemented by using different amplitude and phase configurations
for the various antennas 1014, 1024, i.e., different values for the
antenna weights. For example, given antenna weights may be used for
a transmit beam and a receive beam; then the transmit beam is
inverted to obtain the receive beam.
[0071] If there is beam correspondence, then the same propagation
channel 151 can be addressed by inverting receive and transmit
beams. Reciprocity between transmitting and receiving on a given
beam may be provided for. The path loss of different
directions--e.g., UL and DL--along a given propagation channel 151
is approximately the same. Beam correspondence may correlate with
reciprocity: In FIG. 2, a scenario including reciprocity of the
propagation channel 151 and, hence, beam correspondence is
illustrated.
[0072] FIG. 2 also illustrates aspects with respect to radar
probing 200. Radar probing 200 is performed by the UE 102. In the
example of FIG. 2, the radar probing 200 is implemented by
pulsed-mode radar ranging including primary radar signals 201
travelling from the UE 102 to an object 203 and further including
secondary radar signals 202 having been reflected by the object 203
travelling from the object 203 to the UE 102. For example,
time-of-flight ranging can be implemented.
[0073] As illustrated, the direction 260 along which the radar
probing 200 is implemented is offset from the beam 311 employed by
the UE 102 to wirelessly communicate with the BS 101. This
corresponds to SDD of (i) wireless communication and (ii) radar
probing. Thereby, interference between (i) wireless communication
and (ii) radar probing can be reduced.
[0074] In FIG. 2, also another UE 299 is illustrated that may
communicate with the BS 101 or another BS or another wireless
communication device using a further wireless link (not illustrated
in FIG. 2). To avoid interference between the radar probing 200 and
the wireless communication of the UE 299, the UE 101 may measure a
spectral power level on the various beams; an increased spectral
power level may be experienced in the direction of the UE 299 due
to the UE 299 accessing the spectrum. Then, the direction 260 can
be offset from the direction of the UE 299, to mitigate
interference. Thus, as a general rule, the direction 260 can be
determined based on the spectral power level measured when
performing a receive beam sweep.
[0075] Alternatively or additionally to such a dependency of the
direction 260 of the radar probing 200 on the spectral power level,
it would also be possible to set the transmit power of the radar
probing 201 based on the measured spectral power level. For
example, if another UE 299 is detected in a given direction due to
an increased spectral power level, then it would be possible to
reduce the transit power of the radar probing 200 in this
direction. This also mitigates interference.
[0076] FIG. 3 is a flowchart of a method of operating a wireless
communication device according to various examples. For example,
the method of FIG. 3 may be executed by a UE, e.g., by the UE 102.
For example, the method may be executed by the control circuitry
1021, 1025 of the UE 102. Alternatively or additionally, the method
may be executed by a BS, e.g., by the BS 101. For example, the
method may be executed by the control circuitry 1011, 1015 of the
BS 101.
[0077] First, at optional block 2001, it is checked whether the
wireless communication device is clear to perform radar probing. As
a general rule, various options are available to implement block
2001.
[0078] In one option, the wireless communication device may test
whether it is out-of-coverage. In other words, it can be checked
whether a wireless communication on a wireless link between the
wireless communication device and a further wireless communication
device is possible. For example, if a distance between the wireless
communication device and the further wireless communication device
is large, then the wireless communication device may be
out-of-coverage and communication on the wireless link may not be
possible due to increased path loss.
[0079] In another option, the wireless communication device may
test whether any signals are received, e.g., from further wireless
communication devices. This may correspond to a listen-before-talk
approach. For example, if--within a given timeframe--no signals are
received, then it can be judged that the wireless communication
device is cleared to perform the radar probing.
[0080] If, at block 2001, it is judged that the wireless
communication device is cleared to perform radar probing, then at
optional block 2005 unrestricted radar probing is performed.
Specifically, at block 2005, the radar probing can be performed
spatially unrestricted, e.g., in any direction that the wireless
communication device chooses to be appropriate. For example,
omni-directional radar probing can be performed.
[0081] Otherwise, if at block 2001 it is judged that the wireless
communication device is not out-of-coverage--i.e., is
in-coverage--, then, at optional lock 2002, a control signal can be
communicated on the wireless link.
[0082] For example, it would be possible that the control signal is
a DL control signal that is received by the UE 102 from the BS 101
(cf. FIG. 2). In other examples, it would be possible that the
control signal is an UL control signal that is transmitted by the
UE 102 to the BS 101 (cf. FIG. 2). In still other examples, it
would be possible that the control signal is a sidelink control
signal.
[0083] The control signal can be indicative of at least one
radar-probing constraint. The at least one radar-probing constraint
can impose certain restrictions on the radar probing. For example,
the radar-probing constraint can include a transmit power
restriction, a timing restriction, and a frequency band restriction
of the radar probing.
[0084] For example, the transmit power restriction may impose an
upper threshold for the transmit power. For example, the timing
restriction may impose an upper threshold for a repetition rate of
the radar probing. For example, the frequency band restriction may
be indicative of certain blocked frequency bands.
[0085] Then, the radar probing can be performed using a transmit
power, a timing, and/or a frequency band in accordance with the
transmit power restriction, the timing restriction and/or the
frequency band restriction. For example, the transmit power of the
radar probing may be set such that it stays below an upper
threshold imposed by the transmit power restriction of the
radar-probing constraint.
[0086] The radar-probing constraint can also include a spatial
restriction for one or more radar-probing directions. Then, the
radar probing can be performed along one or more radar-probing
directions in accordance with the spatial restriction. For example,
blocked directions may be spared.
[0087] At block 2003, at least one beam sweep is performed. This is
done to identify one or more beams for wireless communication on
the wireless link. For example, the at least one beam sweep may
include a transmit beam sweep and/or a receive beam sweep.
[0088] Pilot signals may be communicated on multiple candidate
beams as part of the at least one beam sweep. Then, based on a
receive property of the pilot signals, one or more beams may be
identified for the wireless communication.
[0089] At block 2004, semi-unrestricted radar probing is performed.
The radar probing may be semi-unrestricted, because it is performed
along one or more radar-probing directions that are determined, by
the wireless communication device, to be offset from the one or
more beams identified by means of the beam sweep at block 2003,
without a need to obtain further, specific authorization to perform
the radar probing along these specific one or more radar-probing
directions.
[0090] In any case, the radar probing can be in accordance with the
radar-probing constraint indicated by the control signal of block
2002; but, if this constraint is met by the determined one or more
directions, further authorization to perform the radar probing
along the one or more radar-probing directions may not be
required.
[0091] Specifically, the radar probing, at block 2004, may be
performed in response to identifying the one or more beams using
the beam sweep at block 2003. No additional authorization may be
required. Additional control signaling on the wireless link may not
be required. This helps to reduce a control signaling overhead on
the wireless link. At the same time, the interference between the
radio probing and the wireless communication can be reduced.
[0092] As will be appreciated from FIG. 3, the optional
decision-taking process at block 2001 can correspond to a
listen-before-talk approach where, first, (listen) the spectral
power level is measured to determine whether there is a risk of
interference; and, second, (talk) depending on the spectral power
level, an unrestricted or semi-unrestricted access to the spectrum
is implemented.
[0093] FIG. 4 illustrates aspects with respect to a beam sweep 300.
The beam sweep 300 may be performed at block 2003 of FIG. 3.
[0094] As a general rule, the UE 102 may be in connected mode with
a data connection being established between the UE 102 and the BS
101 when performing a beam sweep 300. It would also be possible
that the UE 102 is in disconnected mode where a data connection is
not established between the UE 102 and the BS 101 when performing
the beam sweep 300. Here, it would be possible that the beam sweep
300 is in preparation of a future wireless communication on the
wireless link 111.
[0095] For example, the beam sweep 300 may be a transmit beam sweep
of UL pilot signals 152 or may be a receive beam sweep of DL pilot
signals 152.
[0096] In an example, a transmit beam sweep of the UE 102 may be
time-aligned with the receive beam sweep of the BS 101. In another
example, a receive beam sweep of the UE 102 may be time-aligned
with a transmit beam sweep of the BS 101. Thus, while the BS 101 is
transmitting, the UE 102 may be configured to listen, and vice
versa.
[0097] The beam sweep 300, in the example of FIG. 4, includes three
beams 311, 312, 313. Thereby, a certain beam sweep angle 351 is
implemented. The beam sweep angle 351 is achieved by the opening
angle 352 of each one of the beams 311-313. Depending on the
particular beam sweep, the count of beams, the opening angle 352,
the beam sweep angle 351, etc., can vary.
[0098] The values of the antenna weights used for each one of the
beams 311-313 are predefined in a corresponding CB. Then, e.g., if
beam 312 shows a larger signal strength at the receiver if compared
to beams 311 and 313, the values of the antenna weight used for
subsequent communication on the wireless link 111 may be determined
in accordance with the values of the antenna weights defining the
beam 312. Hence, the beam 312 may be selected from a CB based on
the beam sweep.
[0099] For example, if the beam 312 is selected from the CB, then
it would be possible that radar-probing directions 260 are
determined based on non-selected beams 311, 313, e.g., by aligning
the radar-probing directions 260 with the non-selected beams 311,
313.
[0100] Details with respect to beam sweeps are also illustrated in
FIG. 5.
[0101] FIG. 5 is a signaling diagram of wireless communication on
the wireless link 111. FIG. 5 illustrates aspects with respect to a
transmit beam sweep 301 of DL pilot signals 153 and a receive beam
sweep 302 of the DL pilot signals 153. The beam sweeps 301, 302 are
used to sound the wireless link 111 to facilitate wireless
communication on the wireless link 111.
[0102] Initially, at 5001, a control signal 4001 is transmitted by
the BS 101 and received by the UE 102. The control signal 4001 is,
hence, communicated on the wireless link 111. The control signal
4001 is indicative of at least one radar-probing constraint to be
applied to radar probing 200. As such, 5001 can correspond to block
2002 of FIG. 3.
[0103] After a while, the transmit beam sweep 301 of the DL pilot
signals 153 and a receive beam sweep 302 of the DL pilot signals
153 are implemented. The transmit beam sweep 301--performed by the
BS 101--includes transmit beams 331-333. The receive beam sweep
302--performed by the UE 102--includes receive beams 311-313.
[0104] The transmit beam sweep 301 and the receive beam sweep 302
are time-aligned/synchronized. For example, the BS 101 may first
transmit DL pilot signals on the beam 331; while the BS 101
transmits the DL pilot signals 153 on the beam 331, the UE 102 may
listen for/attempt to receive the DL pilot signals 153 on the beam
311, on the beam 312, and on the beam 313, e.g., sequentially or at
least partially in parallel. Next, the BS 101 may transmit DL pilot
signals 153 on the beam 332; again, while the BS 101 transmits the
DL pilot signals 153 on the beam 332, the UE may attempt to receive
the DL pilot signals 153 on all beams 311-313. Lastly, the BS 101
may transmit DL pilot signals 153 on the beam 333 and the UE 102
may attempt to receive the DL pilot signals 153, again, on all
beams 311-313.
[0105] As a general rule, pilot signals 152, 153 can be indicative
of the particular beam on which they are transmitted such that, at
the receiver, a conclusion can be made on to which transmit beam
provides for a propagation channel 151 with low path loss, at a
given receive beam.
[0106] For example, in the scenario of FIG. 5, the UE 102
identifies the receive beam 313 in combination with the transmit
beam 331 to be associated with a propagation channel 151 having a
comparably small path loss. For example, this can include
measurements of a received signal strength of the DL pilot signals
153. For example, it would be possible to identify the receive beam
313 as the particular beam having the highest received signal
strength.
[0107] Hence, the UE 102 selects the transmit beam 331 and the
receive beam 313. This corresponds to identifying the receive beam
313 to be used by the UE 102 for wireless communication.
[0108] Next, at block 5003, the UE 102 transmit an UL feedback
signal 4002 to the BS 101. The UL feedback signal is indicative of
the transmit beam 331 and optionally indicative of the receive beam
313.
[0109] Then, at 5004, the BS 101 transmits DL data signals 4003
using the transmit beam 331 and the UE 102 receives the DL data
signals 4003 using the receive beam 313. Hence, at 5004, wireless
communication is implemented on the wireless link 111 on the beams
331, 313 identified in the beam sweeps 301, 302.
[0110] FIG. 5 illustrates a scenario where beam correspondence is
provided on the wireless link 111. For this reason, the UE 102 can
assume that a transmit beam 313A that is aligned with the receive
beam 313--i.e., the transmit beam 313A is reciprocal to the receive
beam 313--can also implement wireless communication on the wireless
link 111 along propagation channel 151 associated with a low path
loss. Accordingly, at 5005, the UE 102 transmits UL data signals
4004 using the transmit beam 313A and the BS 101 receives the UL
data signals 4004 using the receive beam 331A that is also aligned
with the transmit beam 331.
[0111] Because there is beam correspondence provided on the
wireless link 111, the UE 102 can conclude that transmitting radio
signals 201 along directions 260 offset from the beams 313, 313A
can provide for SDD with the wireless communication on the wireless
link 111. This mitigates interference.
[0112] In the example of FIG. 5, accordingly, radar probing 200 is
performed at 5006 and again at 5007. A repetition rate 206 defining
a time duration between subsequent instances of the radar probing
200 is illustrated and may be set to be larger than a respective
timing restriction of the radar-probing constraint indicated by the
control signal 4001.
[0113] As illustrated by the polar plots in FIG. 5, the
radar-probing directions 260 are offset from the beams 313,
313A.
[0114] FIG. 6 is a signaling diagram of wireless communication on
the wireless link 111. FIG. 6 illustrates aspects with respect to a
receive beam sweep 303 of UL pilot signals 154 and a transmit beam
sweep 304 of the UL pilot signals 154.
[0115] FIG. 6 generally corresponds to FIG. 5. For example, 5011 of
FIG. 6 corresponds to 5001 of FIG. 5. 5012 generally corresponds to
5002; however, at 5012, the UE 102 performs a transmit beam sweep
304 of UL pilot signals 154 on the transmit beams 311A-313A; and
the BS 101 performs a time-aligned receive beam sweep 303 on the
receive beams 331A-333A.
[0116] Again, the receive beam sweep 303 can include measurements
of the received signal strength of the UL pilot signals 154.
[0117] Then, at 5013, a DL feedback signal 4005 is transmitted by
the BS 101 and received by the UE 102. The DL feedback signal 4005
is indicative of the beam 313A. Subsequently, at 5014 and 5015, the
UE 102 uses the beam 313A and the reciprocal beam 313 to
communicate data signals 4003, 4004 on the wireless link 111; these
beams 313, 313A are identified by the UE 102 based on the feedback
signal 4005.
[0118] 5016 and 5017 corresponds to 5006 and 5007,
respectively.
[0119] FIG. 7 illustrates details with respect to directions
261-263 along which the radar probing 200 is implemented. FIG. 7 is
a polar plot. In FIG. 7, the directions 261-263 and corresponding
transmit powers 281 of the radar probing 200 are illustrated (in
the polar plot of FIG. 7, larger transmit power levels are
associated with larger radial distance from the center of the polar
plot).
[0120] In FIG. 7, radar probing 200 is implemented along
radar-probing directions 261-263. These radar-probing directions
261-263 are offset from the beams 313, 313A used for the wireless
communication on the wireless link 111 and, e.g., determined using
one of the techniques as illustrated in FIGS. 5 and 6.
[0121] FIG. 7 also illustrates aspects with respect to
radar-probing constraints. For example, radar-probing constraints
as illustrated in FIG. 7 could be indicated by the control signal
4001 (cf. FIG. 5 and FIG. 6).
[0122] In the example of FIG. 7, the radar-probing constraints
includes a spatial restrictions 271 for the radar-probing
directions 261-263. Forbidden directions are implemented by the
spatial restriction 271 (illustrated by the dashed areas in FIG.
7). As will be appreciated, the radar-probing directions 261-253
are selected in accordance with the spatial restrictions 271, i.e.,
offset from the forbidden directions.
[0123] In the example of FIG. 7, the radar-probing constraints also
include a transmit power restriction 272. For example, the transmit
power restriction 272 implies a low transmit-power threshold
(dashed lines) on the transmit power for the radar probing 200
along the radar-probing direction 262; and does not imply a low
transmit-power threshold for the radar probing 200 along the
radar-probing direction 263.
[0124] As a general rule, there can be various reasons for imposing
a network-controlled restriction on the transmit power; examples
include knowledge on locations of other wireless communication
devices.
[0125] As illustrated in FIG. 7, the transmit-power restriction 272
indicated by the radar-probing constraint may impose an upper limit
for the actual transmit power used by the UE 102 when radar probing
200. For example, an the scenario FIG. 7, the radar probing 200
uses a transmit power 281 that stays below the respective
transmit-power restrictions 272 for the radar-probing directions
261 and 263. The radar probing 200 uses a transmit power 281 that
reaches the transmit-power restriction 272 for the radar-probing
direction 262.
[0126] Such a concept of using the control signal 4001 to impose
constraints on the radar probing 200 can refer to the
semi-unsanctioned radar probing 200 where the UE 102 is control of
the actual parameters of the radar probing 200 in view of certain
constraints imposed by the wireless communication and/or in view of
certain BS controlled constraints.
[0127] The actual transmit power 281 of the radar probing 200 can
be set within the radar-probing constraints. For example, the
transmit power 281 of the radar probing 200 could be set based on a
received signal strength of the pilot signals 152-154 of the beam
sweeps 300-304. For example, if a low received signal strength is
observed on the beams selected for the wireless communication, then
a comparably low transmit power 281 may be selected in
radar-probing directions adjacent to the selected beams (such as
illustrated in the example of FIG. 7 for the radar-probing
directions 261, 263 which are adjacent to the beams 313, 313A).
[0128] As a general rule, other criteria can be taken into account
when setting the transmit power 281, instead or in addition to the
received signal strength of the pilot signals 152-154. For example,
it would be possible to set the transmit power 281 based on a
spectral power level measured as a part of a receive beam sweep.
Thereby, other UEs 299 transmitting signals that may or may not be
decodable by the UE 101 can be detected and interference can be
mitigated also with respect to those other UEs 299.
[0129] Further illustrated in FIG. 7 is a UE-controlled spatial
restriction 275 of the radar probing 200 (illustrated with a
checkerboard filling in FIG. 7). For example, a receive beam sweep
302 implemented by the UE 102 may comprise measurements of a
spectral power level in the frequency band used for the radar
probing 200. The spectral power level may be associated with
signals communicated by other wireless communication devices, e.g.,
other UEs (cf. FIG. 2 where another UE 299 is illustrated).
[0130] Such other wireless communication devices may not
communicate on the wireless link 111 between the UE 102 and the BS
101. For example, other wireless communication devices connected to
or camping on the same cell as the UE 102 may be communicating with
the BS 101 using respective wireless links. Also, inter-cell
interference for cellular networks may result in an increased
spectral power level of other wireless communication devices
located in adjacent cells.
[0131] Radar probing 200 can cause interference for these other
wireless communication devices. Hence, the spatial restriction 275
and/or the transmit power 281 may be determined based on the
determined spectral power level. As illustrated in FIG. 7, the
radar-probing directions 261-263 are offset from the spatial
restriction 275.
[0132] As a general rule, where the UE 102 is configured to perform
a transmit beam sweep 304 (cf. FIG. 6) to sound the wireless
channel 111, still, the UE 102 could be configured to perform a
receive beam sweep including the measurements of the spectral power
level for the purpose of determining the spatial restriction
275.
[0133] FIG. 8 illustrates aspects with respect to the frequency
band 501 allocated to the beam sweeps 300-304, further with respect
to the frequency band 502 allocated to the wireless communication
on the wireless link 111, as well as further with respect to the
frequency band 503 allocated to the radar probing 200.
[0134] As illustrated in FIG. 8, the frequency band 501 includes
the frequency band 502. Also, the frequency band 503 includes the
frequency band 502.
[0135] By dimensioning the frequency band 503 to have a large
bandwidth, an accuracy of the radar probing 200--e.g., a lateral
resolution--can be increased. At the same time, by implementing the
bandwidth of the frequency band 501 to cover the entire frequency
bands 503 and 502, appropriate identification of beams, as well as
appropriate identification of potential sources of interference of
the radar probing 200 can be ensured.
[0136] FIG. 8 also illustrates a frequency band restriction 279
defining a forbidden frequency band for the radar probing 200. The
frequency band restriction 279 may be part of a radar-probing
constraint indicated by a DL control signal (cf. FIG. 5 and FIG. 6,
control signal 4001).
[0137] Summarizing, techniques have been described in which a UE
performs at least one beam sweep--e.g., a receive beam sweep and/or
a transmit beam sweep--to populate a list with candidate beams for
wireless communication with another wireless communication device,
e.g., a BS or another UE. The at least one beam sweep may be
performed in a wider bandwidth than the one intended for wireless
communication; this may allow a wider bandwidth of the radar
probing, which generally results in an increased resolution of
positioning (cf. FIG. 8).
[0138] According to examples, all beam directions not in the
candidate beam list and/or directions where the spectral power
level is below a threshold can be used for radar probing, at least
if the UE has beam correspondence (cf. FIG. 7).
[0139] As a general rule, the radar probing may use a different
signal shape, bandwidth, and/or timing than the wireless
communication. This is achieved by spatial multiplexing between
radar probing and wireless communication: one or more directions
are used for radar probing that are offset from one or more beams
used for wireless communication. Directions overlapping with the
one or more beams used for wireless communication can be excluded
from radar probing. The transmit power level of the radar probing
may be set such that interference with wireless communication is
avoided (cf. FIG. 7).
[0140] The transmit power level of the radar probing may be
restricted by one or more UE-controlled and/or network-controlled
constraints. For example, the transmit power level may be
dynamically or statically defined by the BS, regulatory defined, or
related to the receive power level of pilot signals of the at least
one beam sweep (cf. FIG. 7).
[0141] The BS may activate constraints for the radar probing using
a control signal. The restrictions may be the power level, time
domain restriction--perhaps the DL beam sweeps shall be avoided--,
frequency-domain based, and/or spatially defined, e.g. restricted
directions (cf. FIGS. 5 and 6).
[0142] The techniques described herein enable the UE to use
waveforms optimized for radar probing which may not be easy to
integrate together with the waveforms used for wireless
communication.
[0143] Although the invention has been shown and described with
respect to certain preferred embodiments, equivalents and
modifications will occur to others skilled in the art upon the
reading and understanding of the specification. The present
invention includes all such equivalents and modifications and is
limited only by the scope of the appended claims.
[0144] For illustration, above various examples have been described
for wireless communication implemented by a communication system
including a UE and a BS. Similar techniques may be readily applied
to other kinds and types of communication systems, e.g., IEEE WLAN,
etc.
* * * * *